1. Field of the Invention
The present invention relates to optical modules.
2. Description of the Background Art
Since Bragg diffraction gratings can selectively reflect the light of specific wavelengths (hereinafter referred to as “Bragg wavelengths”) that satisfy Bragg conditions, they have conventionally been employed as wavelength selective filters in optical communications systems, for example. Such a Bragg diffraction grating is formed by providing a periodic refractive index change at an end region of an optical fiber. The light of the Bragg wavelength determined by the periodic refractive index change is reflected. An optical fiber with such a Bragg diffraction grating formed therein has its one end installed and secured to a mounting member such as a ferrule (Refer for example to Japanese Patent Application Publication No. 2000-353845).
An optical fiber having a Bragg diffraction grating formed therein is firmly fixed to a mounting member such as a ferrule by applying an adhesive between the part of the optical fiber that is located within the ferrule and the interior walls of the ferrule. In such a case, when the optical fiber is secured to the ferrule, such securing causes stress directly on the optical fiber, particularly at the area where a Bragg diffraction grating has been formed, and such stress changes the reflective characteristic of the Bragg diffraction grating.